Light flasher circuit



3 I KEN HASHIMOTO 3,414,767

LIGHT FLASHER CIRCUIT Filed Oct. 20) 1965 United States Patent 3,414,767 LIGHT FLASHER CIRCUIT Ken Hashimoto, Tokyo, Japan, assignor to Fuji Neon Kabushiki Kaisha, Tokyo, Japan, a corporation of Japan Filed Oct. 20, 1965, Ser. No. 498,556 1 Claim. (Cl. 315200) ABSTRACT OF THE DISCLOSURE The present invention realtes to a lighting flasher and more particularly to a lighting flasher so composed that the output terminals of a single-phase full-wave rectifying circuit of diode bridge with diode rectifying elements are connected with a delay circuit which employs a silicon control rectifying element (hereinafter SCR is short therefor). The input terminals of a lighting apparatus are connected in series between the input terminals of said singlephase full-wave rectifying circuit, and thus said lighting apparatus may be turned on and off.

Hitherto, it has been extremely difiicult technically to operate accurately and reliably with a required cycle a conventional lighting switch which employs a discharge lamp to be flashed for the purposes such as advertising, trafiic direction, road marking, buoy positions, railroadcrossing indications, etc.

The present invention is directed to an improved lighting flasher of which the aforementioned defects have been eliminated.

The object of the present invention is to flash quickly with extreme ease and with an accurate frequency a lighting switch for lighting on and off a discharge lamp used in advertising, trafiic direction, road marking, buoy positions, railroad-crossing indications, etc.

Another object of the present invention is to obtain a lighting switch of longer life because of the fact that the present switch is of a very simple structure and therefore is economical and possible to be flashed by contactless operation.

Briefly stated, in accordance with some aspects thereof, the present invention is a lighting flasher characterized by having a delay circuit comprising: a gate resistor connected with the anode and cathode of SCR connected in parallel with a series timing element connected in series with a resistor and a condenser, and also connected with between the connection point of said resistor and condenser and the gate of said SCR; and a lighting device which is composed of a rectifying element and a lighting apparatus connected in series between an alternating current (AC) power source and the input terminal of the single-phase full-wave rectifying circuit connected to the output terminal with said delay circuit so that said delay circuit may flash said lighting circuit.

Now the present invention will be better understood and other objects and additional advantages of the invention will become apparent upon perusal of the following description taken in connection with the drawings, in which:

FIG. 1 is an electrical circuit diagram showing the first embodiment of a lighting flasher realized according to the present invention;

3,414,767 Patented Dec. 3, 1968 FIG. 2 is a voltage wave form of the input terminal of a lighting apparatus;

FIG. 3 is a voltage Wave form that will appear on both ends of the condenser in a delay circuit.

Referring more particularly to the appended drawings, the preferred embodiment of this invention will now be described; however, the following description will be understood to be illustrative of the present invention and not as limiting it to the particular construction shown and described.

The electrical circuit of FIG. 1 shows an embodiment of a lighting flasher according to the present invention. This circuit is composed of a single-phase full-wave rectifying circiut 2, a delay circuit 1 connected with the output terminals 2A, 2B thereof, and a lighting apparatus 3 connected to the input terminals 2C, 2D of said single-phase full-wave rectifying circuit.

It is so arranged that the diode rectifying elements D1, D2, D3, D4 of the single-phase full-wave rectifying circuit 2 are connected in a bridge circuit form having polarities as shown and further are connected with the output terminals 2A, 2B of said bridge so that a DC voltage may be fed to the delay circuit 1 at all times. Said delay circuit is so composed that a series timing element, or circuit, having a variable resistor R1 and a condenser C connected in series with each other is connected in parallel with the anode and cathode of SCR. A variable gate resistor R2 is connected between the gate of the SCR and the connection point of the variable resistor R1 and the condenser C in said series timing element.

The lighting apparatus is provided with input terminals 3A, 3B, in series with an AC power source feeding and the input terminals 2C, 2D of said single-phase full-wave rectifying circuit 2. The lighting apparatus 3 comprises a transformer T whose primary winding 3B is connected across terminals 3A, 3B and whose secondary winding 3D (the high voltage side) supplies voltage to a neon tube 30.

In respect to the electrical circuit of the illustrated embodiment of the present invention so composed as above, when an AC voltage of v. is fed to the alternating current power source AC, the AC voltage will be rectified -by the single-phase full-wave rectifier consisting of the diode rectifying elements to become a DC voltage that will appear between the anode and cathode of the SCR, because the SCR is initially non-conductive.

Said DC voltage will charge the condenser C through the variable resistor R1 and therefore the voltage at both ends of said condenser will become higher and higher gradually and the voltage arising at both ends of said condenser C will be fed to the gate of the SCR through the variable gate resistor R2. Under such circumstances, when the voltage fed to said gate becomes a required discharge voltage, said SCR, although so far non-conductive, turns suddenly conductive and thence becomes inevitably shunted between its anode and cathode by dint of the very low resistance.

Consequently, an electric current will flow between the input terminals of the single-phase full-wave rectifying circuit 2 so that a current flows in the primary winding of the neon transformer T, thus lighting the neon tube 3C connected with the secondary winding of said transformer. When the SCR becomes conductive as a result of said lighting operation, voltage between the anode and cathode of said SCR will be lowered considerably, and consequently, the charge that has been charged into the condenser C will be reversely discharged by way of the variable resistor R1, thus ending in that the gate of the SCR can be fed but only with an insufficient current. In this case, when the current flowing to the SCR by way of the variable resistor R1 is more than 3 the SCR-holding current, said SCR will continue to be conductive but when it is less than that the AC voltage will be zero, and thereupon the SCR will be nonconductive, thus the neon tube of the lighting apparatus will turn off.

The foregoing description has covered the flashing operation of a neon tube in one cycle of the delay circuit, and said operation will bring into effect just a relaxation oscillation-like condition in relation with the delay circuit and the single-phase full-wave rectifying circuit, and therefore, the neon tube will be repeatedly flashed in keeping with said operation. Further, the cycle of switching in said operation may be adjusted extremely easily by variably regulating the variable resistors R1 and R2,

FIG. 2 shows a voltage wave form of the lighting apparatus. The wave form portion 4 is a voltage wave form for lighting the neon sign tube 3C, said wave form being generated on the primary side of the transformer T in the lighting apparatus 3 when the SCR switching means are conductive. The wave form portion 5 is a voltage wave form which appears when the SCR switching means are not conductive to serve as the voltage for mainly charging the condenser C.

FIG. 3 shows a voltage wave form appearing at both ends of the condenser C in the delay circuit. The wave form portion 6 is what appears when a charge accumulated in the condenser C is discharged to the SCR means. The wave form portion 7 represents the condition of the condenser C being charged by said wave form portion 5.

As is clearly evident from FIGS. 2 and 3, the time constant of the delay circuit is not related with the period of the AC power source, except that the time constant of the delay is far longer than the period of the AC power source, so that the neon sign 3C flickers as required.

In order to obtain a sufficiently long time constant of the delay circuit R1, R2 and C may be selected within the following range:

R1: 5K-100K ohms R2: SK-lOOK ohms C: 10-100 tF 4 When R1 and C are so selected that the time constant is shorter than one half the period of the AC power source, an AC wave form is phase controlled at every half cycle and no flashing action is brought into effect; instead there will be produced a smoothly moving dimming action.

What I claim is:

1. A lighting flasher comprising:

(1) a delay circuit comprising (a) a silicon controlled rectifying element,

(b) a series timing circuit comprising a resistor and a condenser connected in series across the anode and cathode of said silicon controlled rectifying element,

(c) a gate resistor connected between the gate of said silicon rectifying element and the connection point of said resistor and condenser of said series timing circuit,

(2) a single-phase full-wave rectifying circuit having input terminals connected to a source of alternating current voltage and a pair of output terminals connected across the anode and cathode of the silicon controlled rectifying element,

(3) and a lighting apparatus in series between one side of the alternating current power source and an input terminal of said rectifying circuit,

(4) the time constant of said delay circuit being longer than the period of said alternating current power source whereby the lighting apparatus in said lighting circuit will flash on and off.

References Cited UNITED STATES PATENTS 2,462,371 2/ 1949 Engle. 3,130,347 4/ 1964 Harpley. 3,201,597 8/ 1965 Balan.

DAVID J. GALVIN, Primary Examiner. 

